This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primate amygdala is a complex brain region comprised of 13 nuclei and cortical regions in the rostral portion of the medial temporal lobe. This grant has funded studies with the overarching goal of defining the cytoarchitectonic organization and intrinsic and extrinsic connections of the macaque monkey amygdaloid complex. We have also been investigating neuropathology in the autistic amygdala. We reported (Schumann et al, 2004) that the amygdala in typically developing boys undergoes a 40% increase in volume between 7 and 18 years of age. This expansion occurs at a time when the cerebral volume decreases by about 10%. In boys with autism, the amygdala reaches its adult size by 7 years and does not increase thereafter. Given the association of the amygdala with a variety of psychiatric disorders including anxiety, depression, autism and schizophrenia, many of which are first manifest during the peripubertal period, it would be valuable to determine the morphological features of the amygdala's postnatal development. It is not feasible, however, to carry out this type of analysis in postmortem human brains.